President Barack Obama is pictured with host David Letterman during a break at a taping of CBS The Late Show with David Letterman, Monday, Sept. 21, 2009, at the Ed Sullivan Theater in New York. (Charles Dharapak, The Associated Press)

WASHINGTON - President Barack Obama is back doing what many believe he does best - communicating his message via high-profile television appearances.

His latest media blitz, which culminated Monday night in his first presidential appearance on the "Late Show With David Letterman," has been aimed at promoting health-care reform directly to the American people in the waning days of a summer of blistering nationwide debate.

Obama's appearance on "Letterman," the first ever for a sitting president, was apparently meant to reach those who managed to avoid seeing him on the political talk-show circuit Sunday, when he appeared on no fewer than five different broadcasts.

Some wonder what took him so long.

"President Obama is certainly our nation's first talk show-friendly president," said Patrick Egan, a politics professor at New York University.

"The Obama administration has come under criticism all summer for not putting a public face on this huge legislative priority; for better or for worse, Obama hasn't been seen or heard much on the issue over the past couple of months. And so they're getting their turn at bat to make their case."

Not everyone was greeting Obama's media blitz with open arms - notoriously right-wing news outlet Fox News was left out of the Sunday morning ratings bonanza when it was denied a presidential interview for "Fox News Sunday."

"They are the biggest bunch of crybabies I have dealt with in my 30 years in Washington," Chris Wallace, the show's host, complained to colleague Bill O'Reilly on his show, "The O'Reilly Factor."

Wallace - son of "60 Minutes" legend Mike Wallace - was referring to suggestions that the Obama administration was punishing the channel's corporate sibling, Fox TV, for its failure to go live to the president's address to Congress two weeks ago.

"We figured Fox would rather show 'So You Think You Can Dance' than broadcast an honest discussion about health insurance reform," White House spokesman Josh Earnest told ABC News about the reason Fox News wasn't offered an interview.

"Fox is an ideological outlet where the president has been interviewed before and will likely be interviewed again. Not that the whining particularly strengthens their case for participation any time soon."

Obama's 15-minute interviews ran on CNN, CBS, NBC, ABC and the Spanish-language Univision. Conducted from the White House in the Roosevelt Room, the president was peppered with questions not just on health-care reform, but also on his picks for the World Series, the situation in Afghanistan and the role his race is playing in the attacks being levelled against him by his conservative opponents.

On "Letterman" on Monday night, Obama joked about suggestions that vitriolic opposition to his health-care reform plans are fuelled by racism.

"First of all, I think it's important to realize that I was actually black before the election," Obama said to guffaws from Letterman and his audience.

Responded Letterman: "How long have you been a black man?"

Talking about socialized medicine, Letterman remarked that comparisons have been made to Great Britain and Canada, a notion that panics critics, but to him, doesn't seem so bad.

"Canadians don't seem to mind it," Obama noted as a raucous cheer of support went up from the studio audience.

"Seem to be some Canadians here, " Obama remarked.

The president's blitz has been derided by Sen. Lindsey Graham, a South Carolina Republican who accused Obama of appearing "on everything but the Food Channel."

What's truly odd, said Egan, is that the president doesn't have anything to genuinely promote on the health-care reform front.

"There isn't really a legislative proposal to sell to the American public right now, and that's one of the challenges for him," he said.

"If you don't have the actual specifics on the table, it's hard to make the case."

The Senate finance committee will vote this week on a health-care plan from Democratic chairman Max Baucus to expand coverage and control costs. Baucus's proposal would cut Medicare and Medicaid spending by about US$500 billion over 10 years, something he insists would lead to greater efficiency, not reduced benefits.

But the proposal has been met with a lukewarm reception by Democrats and Republicans alike.

Presidents don't usually have much success in changing voters' minds on issues like health care, Egan said - even one as gifted in public relations as Obama.

"Presidents aren't very good at changing public opinions of anything, but they are good at making Americans understand that an issue is important and deserves their attention," he said.

"The question is, will that be enough to put pressure on Congress to actually do something about health-care reform?"